Not all motionlaws have a SegmentRange.
SegmentRange parameters edit the start and end of the mathematicalfunction that defines the motionlaw.
SegmentRange does NOT change the SegmentWidth.
SegmentRange does not change the Xaxis values of the SegmentStart or SegmentEnd, and thus the SegmentWidth does not change.
Start and End Segment Ranges 
Segment Ranges  available with a selection of Traditional MotionLaws. The parameters are:
0 ≤ Start Range < End Range ≤ 1 

Notes:


The images shows the acceleration graph of a Modified Sinusoid motionlaw. Image 1 Default SegmentRange parameter values.
SegmentWidth does not change. 

Image 2
A StartRange = 0.2 removes 20% at the start of the ModifiedSinusoid segment mathematically function 

Image 3
The EndRange = 0.8 removes 20% at the end of the ModifiedSinusoid segment. The SegmentWidth does not change. 

see also: Segment Editor: SegmentWidth, Segment Editor: Parameters 
Symmetrical Motions The crossover [or viceversa] is usually at the midpoint of the SegmentWidth. Asymmetrical Motions The crossover is not at the midpoint of the Segment Width. When to use Asymmetrical Motions You want the mechanism tool to accelerate quickly from a dwell until it reaches a peak velocity that is sooner than the midpoint of the motionlaw, It is then followed with a deceleration that is longer than the standard deceleration duration. Or viceversa. 

You can model an asymmetrical motion with two segments that have the same motion law  for example a Modified Sinusoid. Orange Line graph :Symmetrical ModSine MotionLaw : λ = 0.5 This motionlaw is usually specified with one standard ModSine segment. However, here, it has two ModSine segments. Segment 1 Machine angle: 0  180º [ 0  0.5 of total duration] Displacement : 0  50 units Segment Ranges = 0 and 0.5. Segment 2 Machine angle: 180  360º [ 0.5  1.0 of total duration] Displacement : 50 100 units Segment Ranges = 0.5 and 1. Black Line graphAsymmetrical ModSine MotionLaw : λ = 0.25 Crossover @ 0.25 = 90º machine angle. It also two ModSine segments: Segment 1: Machine angle: 0  90º [0  0.25 of total duration] Displacement : 0  25 units Segment Ranges : 0 and 0.5. Segment 2: Machine angle: 90  360º [0.75  1.0 of total duration] Displacement : 75  100 units Segment Ranges = 0.5 and 1. Characteristics Values of Asymmetrical MotionLaw. Velocity : No Change to Symmetrical MotionLaw. Acceleration: Segment 1 : Cas = Ca / 2λ ; Acceleration: Segment 2 : Cas = Ca / 2(1λ) 